<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        alert('接下来是两个数的加法运算请你分别输入两个数')
        let num1 = Number(prompt('请输入第一个数字'))
        let num2 = Number(prompt('请输入第二个数字'))
        // 或者是这样let num1 = +prompt('请输入第一个数字')
        let sum = num1 + num2
        document.write(`他们的和是${sum}`)
    </script>
</body>

</html>